UK native Andy Byford will take over as transit boss on Tuesday.

UK native Andy Byford starts Tuesday, joining a team of Metropolitan Transportation Authority executives that is fairly new and in the middle of an ambitious $800 million subway action plan that agency brass believe is putting the brakes on the subway’s downward spiral.

But that work didn’t keep the subway from melting down during a brutal cold spell that led to heavy delays, reroutes, broken signals and rails.

Transit watchers hope Byford, 52, makes good use of his experience managing transit in London, Sydney, Australia, and most recently in Toronto.

“We’re desperate for a turnaround artist,” said Jon Orcutt, a former city transportation policy official and advocacy director at the nonprofit Transit Center.

“You haven’t seen visible change since Lhota came in,” Orcutt said. “You’ve seen plenty of excuse-making.”

Veronica Vanterpool, an MTA board member representing the city, said Byford is no newbie in New York, having worked with him as members of Gov. Cuomo’s 2014 Transportation Reinvention Commission.

“We’ve been compared most negatively, recently, to these global systems, in a variety of different ways, whether it’s cost of construction per mile, whether it’s the technology in our system,” Vanterpool said. “Now we have the expertise to bring that to our system and to help infuse some new ideas and fresh perspective again.”

An MTA spokesman said Byford was unavailable for an interview.

“We are extremely excited to welcome Andy Byford — a world-class transportation leader — to New York City Transit,” MTA spokesman Jon Weinstein said in a statement.

The MTA did release a two-minute video message from Byford on Thursday laying out his key priorities as president of NYC Transit.

“The pinnacle of my career, to be working for one of the world’s greatest transit authorities in a city that I love.”

First on the list: subway performance.

“I’m well aware of the controversies around subway performance in recent months,” Byford said, while touting Lhota’s subway action plan.

He also vowed to tackle declining bus ridership and improve punctuality, while improving accessibility for people with disabilities and mobility issues.

His “signature policy,” though, will be to improve the relationship between the transit authority’s 50,000 workers and management.

“You’ll see a lot of me out and about in the lunchrooms and out on the system,” Byford said. “I will expect my managers to manage you in a modern and enlightened way.”

Roger Toussaint, the former Transport Workers Union Local 100 chief who led the 2005 transit strike, welcomed the outreach.

“Taking Byford at his word, it would be important as there now is an abiding sense that [transit authority] management has returned to the days of tutelage over transit employees and to treating the riders like cattle,” Toussaint said in an email.

Steve Munro, a Toronto native and transit writer for more than a decade, said that Byford earned a reputation as an active transit executive who fought to bring more money to critical transit repair needs and a consultant to turn around a mismanaged project to modernize its signals.

Munro also said that Byford has a penchant for 5-year plans.

“Watch what kind of a recovery plan he puts in place and then, by analogy to his advocacy abilities, how well he is able to sell it politically and find funding,” Munro said. “And make sure the funding actually sticks to it and doesn’t get clawed away for whatever next week’s pet project is.”